1. Field of the Invention
This invention pertains to a machine and method for inserting or removing bushings, preferably rubber bushings from track shoe bores of a tracked vehicle, and for reworking the bores if damaged.
2. Description of Prior Art
In the past, rubber bushings formed by rubber rings bonded to metal sleeves have been inserted into two parallel groups of cylindrical bushing receiving bores of metal track shoes by two separate push rods powered by one or more hydraulic rams. It was believed that in order to provide the correct angular relationship of the octagonal flats in each group of bushings, that a separate push rod was required for each group since the angle of the flats in one group must be complementary to the angles of the flats in the other group relative to a common plane. Because of the resilience of the rubber, the bushings were necessarily pushed a computed distance beyond their desired location in the bores by the two rams, and upon release of pressure were allowed to spring back into their desired axial positions in the bores. In the prior art devices no provision was made for adapting the push rods to pull the bushings to a precise axial position in the bores in the event the bushings were inadvertently pushed beyond their desired final position in the bores.
When track shoes require rebuilding because of worn bushings and/or partially flattened or otherwise damaged bushing bores, the prior art bushing insertion machines were not provided with means to rebuild the bores after the bushings had been removed. A separate machine was provided to perform this rebuilding function.
Although no publications have been found disclosing the above types of machines, the following patents are somewhat pertinent to the art of making or rebuilding crawler type tractor shoes and tracks made from a plurality of interconnected shoes.
U.S. Pat. No. 1,986,493 which issued to Abramson et al. on Jan. 1, 1935 discloses a two plunger portable press for removing or inserting tracks in a crawler type tractor, with one plunger associated with the bores at one end of a shoe and the other plunger associated with the bores at the other end of the shoe. The plunger not only inserts and/or removes bushings but also inserts and/or removes the pins.
U.S. Pat. No. 2,020,162 which issued to Rodgers on Nov. 5, 1935 discloses a hydraulic press used for replacing worn pins and bushings from tracks of crawler type tractors. The press includes a spring return piston having a small diameter push rod ram which pushes out the pins when the track is being held from movement by a thrust plate. An adaptor of larger diameter is used to push out the bushings. However, this patent does not disclose a ram which will both push and pull, nor does it disclose a push rod or ram that is arcuately shifted to handle both bores in a track shoe without first repositioning the shoe.
U.S. Pat. No. 2,387,551 which issued to Abramson et al. on Oct. 23, 1945 discloses a machine for disassembling and re-assembling tracks of the type wherein the side links of each shoe are separate pieces that are held together by press-fitted bushings and pins rotatable in the bushings. The links are supported by suitable clamp means, and a single push rod is used but is not pivoted between the two groups of bores in each shoe.
U.S. Pat. No. 2,392,251 which issued to Matthews on Jan. 1, 1946 discloses a tractor tread dismantler which dismantles a tread made from large rubber shoes having parallel holes therein which receive rods that have keyways near their ends. It is noted that during assembly or disassembly of the shoes that a key having tapered edges is bolted to metal links of the chain to engage flats of the keyways and maintain the flats at predetermined angles relative to each other.